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Calcium carbonate (CaCO 3 ) occurs in two major polymorphs: rhombohedral calcite and orthorhombic aragonite, the latter is thermodynamically metastable. In this study, we first prepared aragonite needle-like particles by introducing CO 2 -containing gas into Ca(OH) 2 aqueous slurry. Then, the resulted aragonite particles were heat treated at 500 • C for 1 h, in order to induce the aragonite-calcite phase transition. Particle structures before and after the heat treatment were characterized mainly by powder X-ray diffractometry (XRD), field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). We found that single-crystalline calcite needle-like particles with zigzag surface structures can be fabricated using the phase transition.

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